1. Technical Field
The present invention relates to a gas packing bag structure, and more particularly to a gas stop structure capable of repeated inflation and deflation.
2. Related Art
A gas stop valve is disposed in a gas packing bag formed of enclosed plastic films through heat-seal bonding. The gas packing bag may be inflated with gas from outside through the gas stop valve. Furthermore, the gas stop valve stops air backflow to prevent the gas inside the packing bag from leaking. The gas stop valve is generally formed of two films partially adhered to each other with a gas passage being formed between the two films by means of heat-seal bonding, so that the packing bag may be inflated with gas through the gas passage. As the packing bag is filled with more and more gas, the pressure inside the packing bag gradually increases. Consequently, when the inflation stops, the two films of the gas stop valve are adhered under the gas pressure, thereby preventing the gas inside the packing bag from escaping.
During deflation of the gas packing bag using a gas stop valve structure, generally, a gas tube must be inserted into the packing bag through the gas passage of the gas stop valve for discharge. However, in practical applications, as the two films of the gas stop valve are adhered under the gas pressure inside the packing bag, it is very difficult to insert the gas tube into the packing bag through the gas passage of the gas stop valve for discharge. In some cases, the gas tube might even damage the gas stop valve (for example, the gas tube pierces through the gas stop valve to damage the films thereof), and cause gas leakage from the packing bag. Furthermore, the gas stop valve is formed of two films. When the gas passage is formed through heat-seal bonding of the two films, the gas passage has a texture preventing the gas tube from being placed in the gas passage. As a result, deflation becomes impossible and the packing bag cannot be inflated and used again, causing inconvenience to users of such a gas packing bag.